WO2004029328A1

WO2004029328A1 - Method of electroless plating

Info

Publication number: WO2004029328A1
Application number: PCT/JP2003/006499
Authority: WO
Inventors: Yoshinori Marumo; Hiroshi Sato; Miho Jomen
Original assignee: Tokyo Electron Limited
Priority date: 2002-09-27
Filing date: 2003-05-23
Publication date: 2004-04-08
Also published as: AU2003241757A1; CN1685081A; KR20050059178A; JP2004115885A

Abstract

A method of elctroless plating, which comprises forming catalytically active nuclei comprising a catalytically active material having a catalytic activity toward a reducing agent contained in an electroless plating solution on a diffusion inhibiting layer (such as a barrier layer), and then carrying out an electroleless plating using the electroless plating solution. The method allows the formation of an electrolessly plated coating on a barrier layer through the acceleration of the reaction of a reducing agent contained in an electroless plating solution by catalytically active nuclei.

Description

Description book Electroless plating method

Technical field

The present invention relates to an electroless plating method for forming an electroless plating film. Background art

Wiring is formed on the semiconductor substrate when producing a semiconductor device

As the degree of integration of semiconductor devices increases, the miniaturization of wiring is in progress, and in response to this, development of wiring creation technology is being carried out. For example, as a method of forming a copper wiring, a dual damascene method in which a wiring and an interlayer connection are formed by forming a copper seed layer by sputtering and embedding a groove or the like by electric plating has been put to practical use. In this method, it is difficult to form an electrical film on the surface to be plated where the seed layer is not formed.

On the other hand, there is an electroless plating method as a plating method which does not require a shield layer. The electroless plating forms a plating film by chemical reduction, and the plating film formed can act as an autocatalyst to continuously form a plating film made of a wiring material. In electroless plating, it is not necessary to form a seed layer in advance, and there is a possibility that the plating film may become nonuniform due to nonuniformity of the seed layer (particularly, step coverage in the concave and convex portions). Few.

In order to prevent the diffusion of the wiring material, a barrier layer may be formed on the substrate and a plating film may be formed thereon. For this barrier layer, metal nitrides such as T i N, T a N, etc. are used, and they are inert to electroless plating. Therefore, it is difficult to perform electroless plating on the barrier layer.

Here, in the case of using the nolia layer, by forming the copper first on the nolia layer by sputtering or the like, it is possible to form an electroless copper plating film on the barrier layer. Japanese Patent Laid-Open Publication No. 2001-85434 has been disclosed. Disclosure of the invention

According to the technique disclosed in the above-mentioned document, the same material as the coating film is formed on the barrier layer, and the processing content is limited.

In view of the above, it is an object of the present invention to provide an electroless plating method capable of realizing electroless plating on a barrier layer by various treatments.

A. In order to achieve the above object, according to the electroless plating method of the present invention, there is provided a diffusion limiting layer forming step of forming a diffusion limiting layer on a substrate for limiting diffusion of a predetermined material, and the diffusion limiting layer forming step. At least on part of the diffusion limiting layer formed on the substrate in the layer forming step, has catalytic activity for the oxidation reaction of the reducing agent in the electroless plating reaction, and has different catalytic activity from that of the predetermined material. A catalytically active nucleation step of forming a catalytically active nucleus composed of a material; and the electroless plating solution containing the reducing agent on the substrate on which the catalytically active nucleus is formed in the catalytically active nucleation step. And a step of forming a plating film made of a predetermined material.

After forming an amphiphilic active nucleus made of a catalytically active material having catalytic activity with respect to the reducing agent contained in the electroless plating film on the diffusion limiting layer (for example, barrier layer), an electroless plating solution is used. Perform electroless plating. The reaction of the reducing agent contained in the electroless plating film is promoted by the catalytically active nucleus, and the formation of the electroless plating film can be performed.

Here, the catalytic activity nuclei are formed discontinuously on the diffusion limiting layer. It may be That is, whether the catalytic active nucleus formed on the diffusion limiting layer is continuous (for example, a continuous layer film) or discontinuous (for example, a discontinuous film dispersed in an island shape), the formation of an electroless plating film Can do

B. The electroless plating method according to the present invention has a catalytic activity for the oxidation reaction of a given reducing agent and contains a catalytically active material different from the given material, and restricts the diffusion of the given material. A diffusion limiting layer forming step for forming a diffusion limiting layer on a substrate, and an electroless plating solution containing the predetermined reducing agent on the substrate on which the diffusion limiting layer is formed in the diffusion limiting layer forming step. And a step of forming a plating film made of a predetermined material.

After forming a diffusion limiting layer (for example, a barrier layer) containing a catalytically active material, electroless plating is performed using an electroless plating solution. The reaction of the reducing agent contained in the electroless plating film is promoted by the catalytically active material in the diffusion limiting layer, and the electroless plating film can be formed.

C. The electroless plating method according to the present invention has a catalytic activity for the oxidation reaction of a given reducing agent, consists of a catalytically active material different from the given material, and restricts the diffusion of the given material. A diffusion limiting layer forming step of forming a diffusion limiting layer on the substrate, and an electroless plating solution containing the predetermined reducing agent on the substrate on which the diffusion limiting layer is formed in the diffusion limiting layer forming step. And a step of forming a plating film of the predetermined material using the above-mentioned material.

After forming a diffusion limiting layer (for example, a noble layer) from a material having both catalytic activity and diffusion limiting property, electroless plating is performed using an electroless plating solution. The catalytically active material constituting the diffusion limiting layer accelerates the reaction of the reducing agent contained in the electroless plating film, whereby the formation of the electroless plating film can be performed. Brief description of the drawings

FIG. 1 is a flow chart showing the procedure of the electroless plating method according to the first embodiment.

2A to 2D are cross sectional views showing the cross section of the wafer W in the procedure of FIG.

FIG. 3 is a partial sectional view showing an electroless plating apparatus used for the electroless plating in FIG.

FIG. 4 is a partial cross-sectional view showing a state in which a wafer W or the like installed in the electroless plating apparatus shown in FIG. 3 is inclined.

FIG. 5 is a flow diagram showing an example of a procedure in the case of performing electroless plating using the electroless plating apparatus according to the first embodiment.

FIG. 6 is a partial cross-sectional view showing the state of the electroless plating device when the electroless plating is performed according to the procedure shown in FIG.

FIG. 7 is a partial cross-sectional view showing the state of the electroless plating device when the electroless plating is performed according to the procedure shown in FIG.

FIG. 8 is a partial cross-sectional view showing the state of the electroless plating apparatus in the case where electroless plating is performed in the procedure shown in FIG.

FIG. 9 is a partial cross-sectional view showing the state of the electroless plating apparatus when the electroless plating is performed according to the procedure shown in FIG.

FIG. 10 is a partial cross-sectional view showing the state of the electroless plating apparatus when the electroless plating is performed according to the procedure shown in FIG.

FIG. 11 is a partial cross-sectional view showing the state of the electroless plating apparatus when the electroless plating is performed according to the procedure shown in FIG.

FIG. 12 is a partial cross-sectional view showing the state of the electroless plating apparatus when the electroless plating is performed according to the procedure shown in FIG. FIG. 13 is a flowchart showing the procedure of the electroless plating method according to the second embodiment.

14A and 14B are cross-sectional views showing the cross section of the wafer W in the procedure of FIG.

FIG. 15 is a flowchart showing the procedure of the electroless plating method according to the third embodiment.

FIGS. 16A and 16B are cross-sectional views showing the cross section of the wafer W in the procedure of FIG. MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the electroless plating method according to the embodiment of the present invention will be described in detail with reference to the drawings.

First Embodiment

FIG. 1 is a flow chart showing the procedure of the electroless plating method according to the first embodiment of the present invention. 2A to 2D are cross sectional views showing the cross section of the wafer W in the procedure of FIG.

As shown in FIG. 1, in the electroless plating method according to the first embodiment of the present invention, the wafer W is processed in the order of steps S11 to S13. The details of this process will be described below.

(1) Formation of barrier layer on wafer W (step S 1 1, FIG. 2 A)

A barrier layer is formed on the wafer W. The barrier layer functions as a diffusion limiting layer, and is a barrier for preventing the diffusion of the wiring material (eg, copper). The barrier layer prevents the contamination of the wafer W due to diffusion of wiring material or the like (for example, electoral migration). As the material of this barrier layer, for example, Ta, TaN, W, WN, Ti, Tin can be used. In the wafer w, concaves and convexes for embedding wiring materials such as trenches and vias are appropriately formed, and a barrier layer is formed corresponding to the concaves and convexes. FIG. 2A shows a state in which the barrier layer 2 is formed corresponding to the recess 1. The barrier layer 2 can be formed by, for example, a physical film forming method (sputtering method, vacuum deposition or the like) or a chemical film forming method (CVD method or the like). (2) Formation of catalytically active nuclei on the barrier layer (Step S12, FIG. 2B) Catalytically active nuclei 3 are formed on the barrier layer 2. The catalytically active core 3 is composed of a catalytically active material having an activity as a catalyst for promoting the oxidation reaction of the reducing agent which is the component, particularly the electroless plating solution used in Step S13, It acts as a nucleus (origin) to form. The catalytically active core 3 may be a continuous membrane in the form of a layer or a discontinuous membrane dotted in the form of islands (island).

Here, an example of the catalytically active material constituting the catalytically active nucleus 3 is shown. This catalytically active material can be selected according to the reducing agent used as a component of the electroless plating solution described later.

1) When the reducing agent is formaldehyde: I r, P d, Ag, R u R h, A u, P t

Reaction at electroless plating: 2 HC (OH) ○-+ 20H-

2 e—

2) When the reducing agent is hypophosphite: Au, Ni, Pd, Co, Pt (arranged so that the catalytic activity is higher towards the left (A u> Pt))

Reaction during electroless plating: H ₂ P 0 ₂ — + 2 OH-

_{→ 2 H 2 P 0 3 "} + H 2 † + 2 e - 3) If the reducing agent is a Gurukiokishiru acid: I r, P cU Ag, Ru, R h, A u, P d, P t Reaction during electroless plating: 2 HC (OH) 0-+ 20H 1

→ 2 HC 00 ⁺ + 2 H ₂ 0 + 11 ₂ +

2 θ "

4) When the reducing agent is a metal salt (such as cobalt nitrate): Ag, Pt, Rh, Ir, Pd, Au

5) When the reducing agent is dimethylamine borane: Ni, Pd, Ag, Au, Pt

Reaction during electroless plating: (CH ₃ ) ₂ HN · BH ₃ + 3 H ₂ 0

→ H 3 B 03 + (CH 3) 2 H ₂ N ⁺ + 5 H + + 6 e− (3) Electroless plating of wafer W (step S 13, FIG. 2 C, 2 D) Wafer W Electroless plating is performed to form an electroless plating film. This electroless plating can be performed according to the procedure of FIG. 5 using the apparatus shown in FIG. 3 as described later.

In the initial stage of electroless plating, an electroless plating film is formed on catalytically active nuclei 3 (FIG. 2C). That is, at this stage, when the catalytic active nucleus 3 is a discontinuous film, the electroless plating film also becomes a discontinuous film.

Thereafter, the electroless plating film 4 is grown, and the electroless plating film 4 on the catalytically active core 3 is spread on the surface of the wafer W. That is, even when the catalytic active nucleus 3 is a discontinuous film, the electroless plating films 4 on the catalytic active nucleus 3 are connected to each other to form a continuous film.

When the catalytically active nucleus 3 is a continuous film, it is continuous without necessarily going through the process of forming the non-continuous film electroless plating film 4 as shown in FIGS. 2C and 2D. An electroless plating film 4 is formed.

(Details of the electroless plating device used for electroless plating)

FIG. 3 is a partial cross-sectional view showing the configuration of the electroless plating apparatus 10 used for the electroless plating in step S13. The electroless plating apparatus 10 can perform the electroless plating process on the wafer W which is the substrate, the pretreatment process, the washing process after the plating process, and the drying process using the processing solution.

That is, as the processing solution, in addition to the chemical solution for electroless plating, various liquids such as a pretreatment for plating, a chemical solution for post-treatment, pure water and the like can be included.

As a chemical solution (electroless plating solution) used for the electroless plating, it is possible to use a mixture of the following materials and dissolving in pure water.

1) Metal salt: A material that supplies the metal ions that make up the coating film. The metal salt is, for example, copper sulfate, copper nitrate, or copper chloride when the plating film is copper.

2) Complexing agent: A material for complexing metal and improving its stability in liquid so that metal ions do not precipitate as hydroxide under strong alkalinity. As the complexing agent, for example, HEADTA, EDTA, ED as an amine-based material, and citric acid, tartaric acid, gluconic acid as an organic-based material can be used.

3) Reducing agent: A material for catalytically reducing and precipitating metal ions. As the reducing agent, for example, formaldehyde, hypophosphite, glyoxylic acid, metal salt (eg, cobaltous nitrate), dimethylamine borane, stannic chloride, borohydride compound can be used.

4) Stabilizer: A material that prevents the natural decomposition of the plating solution caused by the non-uniformity of the oxide (in the case of copper film, cupric oxide). As the stabilizer, for example, biviridyl which preferentially forms a complex with monovalent copper, cyanide compound, thiourea, 0-phenanthrin, neoproine can be used as a nitrogen-based material.

5) pH buffer: A material to control the change in pH when the reaction of the plating solution proceeds. For pH buffers, for example, boric acid, carbonic acid, hydroxyl power Rubynic acid can be used.

6) Additives: Additives include materials that promote and suppress the deposition of the coated film, and materials that modify the surface or coated film.

-As a material for suppressing the deposition rate of the coated film and improving the stability of the coating solution and the characteristics of the coated film, use, for example, thiosulfuric acid or 2-MBT as a sulfur-based material. Can.

• As a material for lowering the surface tension of the coating solution and for evenly placing the coating solution on the surface of the wafer W, for example, polyalkylene glycol, polyethylene as a nonionic material of surfactant Glycol can be used.

As shown in FIG. 3, the electroless plating apparatus 10 includes a base 1 1, a hollow mold 1 2, a wafer chuck 20 as a substrate holding unit, an upper plate 30, a lower plate 40, a cup 50, and a nozzle arm 6. 1, 6 2, the inclination adjustment section, the substrate inclination mechanism 70, and the liquid supply mechanism 80. Here, hollow cylinder 12, wafer chuck 20, upper plate 30, lower plate 40, cup 50, nozzle arm 61 and 62 are directly or indirectly connected to base 11. It moves with the base 1 1 and tilts by the substrate tilt mechanism 70.

The wafer chuck 20 holds and fixes the wafer W, and includes a wafer holding claw 21, a wafer chuck bottom plate 23, and a wafer chuck support 24.

A plurality of wafer holding claws 21 are arranged on the outer periphery of the wafer check bottom plate 23 to hold and fix the wafer W.

The wafer check bottom plate 23 is a substantially circular flat plate connected to the top surface of the wafer check support 24, and is disposed on the bottom of the cup 50. Wafer chuck support 24 has a substantially cylindrical shape and has a wafer chuck bottom It is connected to a circular opening provided in the plate 23 and constitutes a rotational shaft of the hollow motor 12. As a result, by driving the hollow motor 12, it is possible to rotate the wafer check 20 while holding the wafer W. Further, as described later, since the cup 50 can move up and down, the wafer chuck 20 disposed at the bottom of the force cup 50 also moves up and down with the cup 50.

The upper plate 30 has a substantially circular flat plate shape, and has a heat sink H (not shown), a treatment solution discharge port 31, a treatment solution inflow portion 32, a temperature measurement mechanism 33, and an elevation mechanism 3 Connected to four.

H is a heating means such as a heating wire for heating the upper plate 30. The heat treatment H corresponds to the temperature measurement result by the temperature measurement mechanism 33 so that the upper plate 30 and hence the wafer W can be maintained at a desired temperature (for example, the range from room temperature to about 60 ° C.) The amount of heat generation is controlled by control means (not shown).

One or more treatment liquid discharge ports 31 are formed on the lower surface of the upper plate 30 and discharge the treatment liquid flowing in from the treatment liquid inflow portion 32.

The treatment liquid inflow portion 32 is on the upper surface side of the upper plate 30, and the treatment liquid flows in, and the treatment liquid that has flowed in is distributed to the treatment liquid discharge port 31. The processing liquid flowing into the processing liquid inflow section 32 can be used by switching the pure water (RT: room temperature) and the heated chemical solutions 1 and 2 (for example, the range from room temperature to about 60 ° C.). In addition, the chemical solutions 1 and 2 mixed in a mixing box 85 described later (in some cases, by mixing a plurality of other chemical solutions including other chemical solutions) can be made to flow into the processing solution inflow portion 3 2.

The temperature measurement mechanism 33 is a temperature measurement means such as a thermocouple embedded in the upper plate 30 and measures the temperature of the upper plate 30.

Lifting mechanism 34 is connected to upper plate 30 and upper plate 30 For example, the distance between the wafer W and the wafer W can be controlled within a range of 0.1 to 500 mm. During electroless plating, the wafer W and the top plate 30 are brought close to each other (for example, the distance between the wafer W and the top plate 30 is 2 mm or less), and the size of the space of these gaps is limited. It is possible to make the processing liquid supplied onto the surface of the wafer W uniform and reduce the amount used.

The lower plate 40 is a substantially circular flat plate disposed to face the lower surface of the wafer W, and the wafer W is supplied by supplying heated pure water to the lower surface in a state close to the wafer W. It can be heated appropriately.

In order to heat the wafer W efficiently, it is preferable that the size of the lower plate 40 be close to the size of the wafer w. Specifically, the size of the lower plate 40 is preferably 80% or more, or 90% or more of the area of the wafer W.

The lower plate 40 has a processing solution discharge port 41 formed at the center of its upper surface, and is supported by a support portion 42.

The processing liquid discharge port 41 discharges the processing liquid that has passed through the inside of the support portion 42. The processing solution can be used by switching between pure water (RT: room temperature) and heated pure water (for example, a range from room temperature to about 60 ° C.).

The support portion 42 penetrates the hollow cylinder 12 and is connected to a lift mechanism (not shown) which is a distance adjustment portion. By operating the elevating mechanism, the support portion 42 and hence the lower plate 40 can be vertically moved up and down.

The cup 50 holds the wafer chuck 20 therein and receives and discharges the processing solution used for processing the wafer W. The cup side 51, the force cup bottom plate 52, the waste pipe It has five three.

The cup side 51 has a substantially cylindrical shape whose inner periphery is along the periphery of the wafer chuck 2 °, and its upper end is located in the vicinity of the upper side of the holding surface of the wafer chuck 20. doing.

The cup bottom plate 52 is connected to the lower end of the cup side 51, and has an opening at a position corresponding to the hollow mirror 12. The wafer chuck 20 is disposed at a position corresponding to the opening. There is.

The waste liquid pipe 53 is connected to the cup bottom plate 52, and the waste liquid (treatment liquid treated with Wah W) is connected to the waste liquid line etc. of the plant where the electroless plating device 10 is installed from the cup 50. It is piping for discharging.

The cup 50 is connected to a lifting mechanism (not shown) and can move up and down relative to the base 1 1 and the wafer W.

The nozzle arms 61 and 62 are disposed in the vicinity of the upper surface of the wafer W, and discharge the fluid such as the processing liquid or air from the opening at the tip end thereof. As the fluid to be discharged, pure water, chemical solution and nitrogen gas can be appropriately selected. Moving mechanisms (not shown) for moving the nozzle arms 61, 62 in the direction toward the center of the wafer W are connected to the nozzle arms 61, 62, respectively. When the fluid is discharged onto the wafer, the nozzle arms 61 and 62 are moved to the upper side of the wafer W, and when the discharge is completed, the nozzle arms 61 and 62 are moved out of the outer periphery of the wafer W. The number of nozzle arms can be one or three or more depending on the amount and type of the chemical solution to be discharged.

The substrate inclining mechanism 70 is connected to the base 1 1, and the base 1 1 is connected to the base 1 1 by raising and lowering one end of the base 1 1, and the wafer chuck 20, wafer W, top plate 30, lower portion connected thereto. Plate 40, cup 50 are inclined, for example, in the range of 0 to 10 ° or 0 to 5 °.

FIG. 4 is a partial cross-sectional view showing the wafer W or the like being tilted by the substrate tilting mechanism 70. It can be seen that the base 11 is inclined by the substrate inclining mechanism 70, and the wafer W or the like directly or indirectly connected to the base 11 is inclined at an angle 0. The liquid supply mechanism 80 is to supply the processing solution heated to the upper plate 30 and the lower plate 40, and the temperature control mechanism 81, the treatment solution tank 82, 83, 84, and the pump P1. ~ P 5, valves V 1 to V 5, mixing box 85 are included. Although FIG. 3 shows the case where the chemical solutions 1 and 2 and two kinds of chemical solutions are used, the number of processing tanks, pumps and valves can be set appropriately according to the number of chemical solutions to be mixed in the mixing box 85. .

The temperature control mechanism 81 has warm water and treatment solution balances 82 to 4 in its interior, and the treatment solution balances 82 to 84 are used to warm the treatment solution (pure water, chemical solutions 1 and 2). The apparatus heats the processing solution appropriately, for example, in the range from room temperature to about 60.degree. For this temperature control, for example, a war bath, a throwing heater, and an external heating can be used as appropriate.

The treatment solution tanks 82, 8 3 and 8 4 are tanks for holding pure water and chemicals 1 and 2, respectively.

The pumps P1 to P3 suck the processing solution from the processing solution reservoirs 82 to 84. In addition, you may perform the liquid feeding from processing solution tank 82-84 by pressurizing process solution tank 82-84, respectively.

Valves V1 to V3 open and close pipes, and supply and stop the treatment liquid. The valves V4 and V5 are for supplying room temperature (not heated) pure water to the upper plate 30 and the lower plate 40, respectively.

The mixing box 85 is a container for mixing the liquid medicines 1 and 2 sent from the processing liquid tanks 83 and 84.

To the upper plate 30, the chemical solutions 1 and 2 can be appropriately mixed in the mixing box 85 and temperature-controlled and sent. In addition, temperature-controlled pure water can be appropriately sent to the lower plate 40.

(Details of electroless plating process) FIG. 5 is a flow chart showing an example of a procedure for performing electroless plating on the wafer W which has been subjected to the steps S11 and S12 described above using the electroless plating apparatus 10. 6 to 12 are partial cross-sectional views showing the state of the electroless plating apparatus 10 in each step when the electroless plating is performed according to the procedure shown in FIG. The procedure will be described in detail below with reference to FIGS.

(1) Holding wafer W (Step S1 and Figure 6)

The wafer W which has been subjected to the steps S11 and S12 described above is held on the wafer mask 20. For example, a suction arm (substrate transfer mechanism) (not shown) having the wafer W suctioned on its upper surface mounts the wafer W on the wafer chuck 20. Then, the wafer W is held and fixed by the wafer holding claw 21 of the wafer chuck 20. In addition, by lowering the cup 50, the suction arm can be moved horizontally below the upper surface of the light W.

(2) Pre-treatment of wafer W (Step S2 and Figure 7)

The wafer W is pretreated by rotating the wafer W and supplying the processing solution to the upper surface of the wafer W from the nozzle arm 61 or the nozzle arm 62.

The rotation of the wafer W is performed by rotating the wafer chuck 20 by means of the hollow cylinder 12. The rotation speed at this time can be, for example, 10 0 to 20 r p m.

The nozzle arm 61 or 62 moves to the upper side of the wafer W and discharges the processing solution. As the processing solution supplied from the nozzle arms 61 and 62, for example, pure water for cleaning the wafer W or chemical solution for catalyst activation processing of wafer W is sequentially supplied according to the purpose of the pretreatment. Ru. The discharge amount at this time may be an amount necessary to form a pad (layer) of the processing liquid on the wafer W, for example, about 100 ml. However, if necessary, increase the discharge amount. No problem. In addition, the processing solution to be discharged may be appropriately heated (for example, in the range of about room temperature to about 60 ° C.).

(3) Heating the wafer W (Step S3 and Figure 8)

The wafer W is heated to keep the wafer W at a temperature suitable for the reaction of the plating solution.

The lower plate 40 is heated to be close to the lower surface of the wafer W (as an example, the distance between the lower surface of the wafer W and the upper surface of the lower plate 40: about 0.1 to 2 mm) Supply pure water heated by mechanism 80. The heated pure water fills the space between the lower surface of the wafer W and the upper surface of the lower plate 40 to heat the wafer W.

By rotating the wafer W during heating of the wafer W, the uniformity of heating of the wafer W can be improved.

By heating the wafer W with a liquid such as pure water, it becomes easy to make the wafer W and the lower plate 40 separately rotate or non-rotate, and contamination of the lower surface of the wafer W is prevented.

The above heating of the wafer W may be performed by other means. For example, the wafer W may be heated by radiant heat of a lamp. Also, in some cases, the wafer W may be heated by contacting the heated lower plate 40 with the wafer W.

(4) Supply of solution (Step S4 and Fig. 9).

The upper plate 30 is heated to be close to the upper surface of the wafer W (as an example, the distance between the upper surface of the wafer W and the lower surface of the upper plate 30: about 0.1 to 2 mm) Supply chemical solution (marking solution) for use (for example, 30 to: L 0 0 m L / min). The supplied plating solution fills the space between the upper surface of the wafer W and the lower surface of the upper plate 30 and flows out to the cup 50. At this time, the temperature is controlled by the upper plate 30 (an example) As the room temperature to about 60 ° C). Preferably, the temperature of the supplied coating liquid is controlled by the liquid supply mechanism 80.

Here, by rotating the wafer W by means of the wafer chuck 20, the uniformity of the metal film formed on the wafer W can be improved. As an example, ゥ W W is rotated by 10 to 50 r p m.

Also, the heating of the upper plate 30 can be preceded by any of the steps S1 to S3 above. By heating the upper plate 30 in parallel with the other steps, the processing time of the wafer W can be reduced.

As described above, by supplying the plating liquid heated to a desired temperature to the upper surface of the wafer W, a marking film is formed on the wafer W. By rotating the wafer W during the supply of this plating solution, the uniformity of the formation of the plating film on the wafer W can be improved.

It is also possible to carry out the following in the supply of the above-mentioned plating solution.

1) The wafer chuck 20 and the upper plate 30 can be tilted by the substrate tilting mechanism 70 before the supply of the plating solution.

By tilting the wafer W, the gas between the wafer W and the upper plate 30 can be quickly removed and replaced with a plating solution. If removal of the gas between the wafer W and the upper plate 30 is incomplete, the cause is that the uniformity of the plating film formed by remaining air bubbles between the wafer W and the upper plate 30 is disturbed. become.

In addition, a gas (for example, hydrogen) may be generated as a result of the formation of the coating film by the plating solution, and bubbles may be formed by the generated gas, which may inhibit the uniformity of the coating film.

Inclination of the wafer W by the substrate inclining mechanism 70 reduces generation of air bubbles and promotes escape of generated air bubbles to improve uniformity of the marking film. It is possible to go up.

2) The temperature of the marking liquid can be changed temporally.

By doing this, it is possible to change the structure and composition in the layer direction of the metal film to be formed.

3) It is possible to supply the plate liquid during the formation of the metal film, not continuously but intermittently. The plating solution supplied onto the wafer W can be efficiently consumed to reduce the amount used.

(5) Cleaning wafer W (Step S 5 and Fig. 10) ₀

The wafer W is cleaned with pure water. This cleaning can be performed by switching the processing solution discharged from the processing solution discharge port 31 of the upper plate 30 from the plating solution to pure water. At this time, pure water can be supplied from the processing solution discharge port 41 of the lower plate 40.

The nozzle arms 61 and 62 can also be used to clean the wafer W. At this time, the supply of the plating solution from the processing solution discharge port 31 of the upper plate 30 is stopped, and the upper plate 30 is separated from the wafer W. Thereafter, the nozzle arms 61, 62 are moved to above the wafer W to supply pure water. Also at this time, it is preferable to supply pure water from the processing solution discharge port 41 of the lower plate 40.

By rotating the wafer W during the above-described cleaning of the wafer W, the uniformity of the cleaning of the wafer W can be improved.

(6) Drying of the wafer W (step S6 and FIG. 1 1).

The supply of pure water to the wafer W is stopped, and the pure water on the wafer W is removed by rotating the wafer W at high speed. In some cases, nitrogen gas may be jetted from the nozzle arms 61 and 62 to accelerate the drying of the wafer W.

(7) Removal of wafer W (step S7 and FIG. 12).

After drying of the wafer W is completed, the wafer chuck 20 Holding is stopped. Thereafter, the wafer W is removed from the wafer chuck 20 by a suction arm (substrate transfer mechanism) not shown.

Second Embodiment

FIG. 13 is a view showing steps of the electroless plating method according to the second embodiment of the present invention. FIGS. 14A and 14B are cross-sectional views showing the cross section of wafer W in the process of FIG.

As shown in FIG. 13, in the electroless plating method according to the second embodiment of the present invention, the wafer W is processed in the order of steps S 21 to S 22. The details of this processing procedure are described below.

(1) Formation of barrier layer on wafer W (Step S 21, FIG. 14 A) A barrier layer 2 a is formed on the wafer W. In this barrier layer 2a, a non-catalytic material having no catalytic activity for the reducing agent of the non-electrolytic plating solution is mixed with a catalytically active material having a catalytic activity for the reducing agent of the non-electrolytic plating solution ( — Used as

As the non-catalytically active material, for example, any one of T a, T a N, W, W N, T i and T i N is used. By doping the non-catalytically active material with the catalytically active material, catalytic activity can be imparted to the noble layer 2a.

As the catalytically active material, the catalytically active material shown in the first embodiment can be selected according to the reducing agent of the nonelectrolytic plating solution.

The formation of the barrier layer 2a can be performed, for example, by a physical film forming method. Specifically, the target is a mixture of a noncatalytic material and a catalytic material (or a combination of noncatalytic material and catalytic material at the same time) by a sputtering method. , Nolia layer 2 a can be formed. This can also be done by vacuum evaporation (co-evaporation) with simultaneous evaporation of non-catalytic and catalytically active material.

(2) Electroless plating of wafer W (Step S 2 2, Fig. 1 4 B) Electroless plating is performed on the wafer W to form an electroless plating film 4 a. In this case, the catalytic activity is imparted to the barrier layer 2a based on the doped catalytic active material, so that the electroless plating film 4a is formed on the barrier layer 2a.

Third Embodiment

FIG. 15 is a flowchart showing the steps of the electroless plating method according to the third embodiment of the present invention. 16A and 16B are cross-sectional views showing the cross section of wafer W in the process of FIG.

As shown in FIG. 15, in the electroless plating method according to the third embodiment of the present invention, the wafer W is processed in the order of steps S 31 to S 32. The details of this processing procedure are described below.

(1) Formation of barrier layer on wafer W (Step S 3 1, Fig. 16 A)

Barrier layer 2 b is formed on wafer W. The barrier layer 2 b is composed of a catalytically active material having catalytic activity with respect to the reducing agent of the electroless plating solution.

As the catalytically active material, the catalytically active material shown in the first embodiment can be selected according to the reducing agent of the non-electrolytic plating solution.

The barrier layer 2 b can be formed, for example, by a physical deposition method (for example, a sputtering method, a vacuum evaporation method) or a chemical deposition method (for example, a C V D method).

(2) Electroless plating of wafer W (Step S32, Fig. 16 B)

Electroless plating is performed on the wafer W to form an electroless plating film. In this case, since the catalytically active material constituting the barrier layer 2 b has catalytic activity, the electroless plating film 4 b is formed on the noble layer 2 b.

(Example 1)

Metal salts and reductants that make up the electroless plating solution, copper salts, gli Using copper xylic acid, a copper electroless plated film was formed according to the procedure corresponding to the third embodiment (the barrier layer is composed of a catalytically active material).

Specifically, electroless plating of copper was performed for each of the underlayer (varier layer) Ru, Ag, Pt, V, In, Ir, Co, and Rh. In addition, as a comparative example, copper electroless plating was performed also in the case where the base was Cu, TaN, TiN, W, WN, and Ta.

When the underlayer is Ru, Ag, Pt, or Ir, all showed better adhesion and deposition rate than the underlayer with Cu. In particular, when the substrate is Ru or Ag, the adhesion is better than when the substrate is Cu.

On the other hand, WN and T a did not precipitate Cu itself. Also, in the case where the base is Ta N, T i N, or W, although the formation of Cu is carried out, it is hard to say that the adhesion to the base of the formed Cu is good.

(Example 2)

A copper salt and a metal salt (cobalt nitrate) are used for each of the metal salt and the reducing agent constituting the electroless plating solution, and copper is applied according to the procedure corresponding to the third embodiment (the barrier layer is composed of a catalytically active material) The electroless plating film was formed.

Specifically, electroless plating of copper was performed for each of Ag, Ir, and Rh as the base (barrier layer). In addition, as a comparative example, electroless plating of copper was performed also when the base was Cu, TaN, TiN, W, WN, V, Co, In, Ru, Pt.

When the underlayer is Ag, Ir, or Rh, all showed better adhesion and deposition rate than the case where the underlayer is Cu. In particular, when the base was Ag, the adhesion was better than when the base was Cu.

On the other hand, when the base was Ta, TaN, Tin, W, WN, V, In, Ru, deposition of Cu itself was not performed. When the substrate is Pt, although Cu formation is performed, it is not sufficient. Also, background In the case of C o and R h, although the formation of C u is performed, it is difficult to say that the adhesion of the formed C u to the base is good.

(Other embodiments)

Embodiments of the present invention are not limited to the above-described embodiments, and can be extended or modified. Extended and modified embodiments are also included in the technical scope of the present invention.

For example, a glass plate or the like other than the wafer W can be used as the substrate. Industrial applicability

The electroless plating method according to the present invention can realize electroless plating on a barrier layer by various treatments, and can be used industrially.

Claims

The scope of the claims

1. a diffusion limited layer forming step of forming a diffusion limited layer on the substrate which limits diffusion of a predetermined material,

At least a portion of the diffusion limiting layer formed on the substrate in the diffusion limiting layer forming step, has catalytic activity for the oxidation reaction of the reducing agent in the electroless plating reaction, and the predetermined material A catalytically active nucleation step of forming catalytically active nuclei composed of different catalytically active materials, and

A plating film forming step of forming a plating film made of the predetermined material using an electroless plating solution containing the reducing agent on the substrate on which the catalytic activation nucleus is formed in the catalytic activation nucleation step; ,

An electroless plating method comprising

2. The electroless plating method according to claim 1, wherein the catalytically active nuclei are formed discontinuously on the diffusion limiting layer.

3. The predetermined reducing agent is either formaldehyde or glyoxylic acid, and the catalytically active material contains at least one of Ir, Pd, Ag, Ru, Rh, Au, Pt, and Ti. Include

The electroless plating method according to claim 1.

4. The predetermined reducing agent is hypophosphite, and the catalytically active material contains at least one of Au, Ni, Pd, Ag, Co, Pt.

The electroless plating method according to claim 1.

5. The predetermined reducing agent is a metal salt, and the catalytically active material contains at least one of Ag, Rh, Ir, Pd and AUt.

The electroless plating method according to claim 1.

6. The predetermined reducing agent is dimethylamine borane, and the catalytically active material contains at least one of Ni, Pd, Ag, Au and Pt. The electroless plating method according to claim 1.

7. A diffusion limiting layer is formed on the substrate which has catalytic activity for oxidation reaction of a given reducing agent and which contains a catalytically active material different from the given material and which limits the diffusion of the given material. A limiting layer forming step,

A plating film is formed on the substrate on which the diffusion limiting layer is formed in the diffusion limiting layer forming step, using the electroless plating solution containing the predetermined reducing agent to form the plating film made of the predetermined material. Step and

An electroless plating method comprising

8. The predetermined reducing agent is either formaldehyde or glyoxylic acid, and the catalytically active material contains at least one of Ir, Pd, Ag, Ru, Rh, Au, Pt, and Ti.

The electroless plating method according to claim 7.

9. The predetermined reducing agent is hypophosphite, and the catalytically active material contains at least one of Au, Ni, Pd, Ag, Co and Pt.

The electroless plating method according to claim 7.

1 0. The predetermined reducing agent is a metal salt, and the catalytically active material contains at least one of Ag, R h, I r, P d, Au, P t

The electroless plating method according to claim 7.

1 1. The electroless plating method according to claim 7, wherein the predetermined reducing agent is dimethylamine borane, and the catalytically active material contains at least one of Ni, Pd, Ag, Au and Pt.

1 2. A diffusion limiting layer is formed on a substrate which has catalytic activity for oxidation reaction of a given reducing agent, is composed of a catalytically active material different from the given material, and restricts the diffusion of the given material. A limiting layer forming step,

From the predetermined material using the electroless plating solution containing the predetermined reducing agent on the substrate on which the diffusion restriction layer is formed in the diffusion restriction layer forming step Forming a plating film forming the plating film;

An electroless plating method comprising

1 3. The predetermined reducing agent is either formaldehyde or glyoxylic acid, and the catalytically active material is at least one of Ir, Pd, Ag, Ru, Rh, Au, Pt, and Ti. Include

The electroless plating method according to claim 1.

14. The predetermined reducing agent is hypophosphite, and the catalytically active material contains at least one of Au, Ni, Pd, A :, Co, Pt.

The electroless plating method according to claim 1.

1 5. The predetermined reducing agent is a metal salt, and the catalytically active material contains at least one of Ag, R h, I r, P d, Au, P t

The electroless plating method according to claim 1.

1 6. The electroless metal according to claim 12, wherein the predetermined reducing agent is dimethylamine borane, and the catalytically active material contains at least one of Ni, Pd, A :, Au, Pt. Tsuki way.